Liquid-crystalline polyorganosiloxanes containing (meth)acryloxy groups have been prepared by the addition of allyl acrylate or allyl methacrylate to organo-hydrogen-polysiloxanes. (See EP-B 0,066,137 U.S. Pat. No. 4,388,453 H. Finkelmann et al, Consortium fur elektrochemische Industrie GmbH).
Methacryloxy and acryloxy groups are introduced into liquid-crystalline polyorganosiloxanes so that the latter can be three-dimensionally crosslinked. This crosslinking can occur for example by radical reaction or ionic reaction at the ethylenic double bonds of the (meth)acryloxy groups. Thus, in order to be able to obtain a high-grade three-dimensionally crosslinked liquid-crystalline polyorganosiloxane, it is desirable to introduce as high as possible proportion of (meth)acryloxy groups into the polyorganosiloxane.
If, however, liquid-crystalline polyorganosiloxanes having a high content of (meth)acryloxy groups are prepared according to the prior art processes mentioned above, only hazy and rough films can be produced with these materials after they have been oriented.
Therefore, it is an object of the present invention to provide liquid-crystalline polyorganosiloxanes having (meth)acryloxy functional groups and compositions containing the said polyorganosiloxanes, which are not hazy even with a high proportion of (meth)acryloxy groups. Another object of the present invention is to provide polyorganosiloxanes of the type mentioned above, from which smooth films can be produced. A further object of the present invention is to provide high-grade three-dimensionally crosslinked clear liquid-crystalline polyorganosiloxanes.